Process of refining copper



Patented Oct. '18, 1932 UNITED STATES PATENT OFFICE JAMES W. SCOTT OFCHICAGO, ILLINOIS, ASSIGNOB 'IO WESTERN ELECTRIC COMPANY, INCORPORATED,OI YORK, N. Y., A CORPORATION OF NEW-YORK rnocnss or mmme corrm IoDrawing.

This invention relates to a rocess of refinloading material the desiredelectrical and magnetic properties. Tough pitch copper, by reason of itshigh electrical conductivity, is ordinarily used in forming theconductors or core in such telephone cable, and when the cable issubjected to the heat treatment above mentioned, the copper isembrittled since tough pitch copper contains a copper-copper oxideeutectic (01101120) the oxygenofwhich reacts with the reducing gas todisrupt the copper crystals and weaken the metallic.

structure of the copper. It is, therefore, very desirable to provide acopper having the lowest possible oxygen content thereby eliminatingthis deleterious reaction when heated in the presence of a reducing gas.

An object of this invention is the produc tion of copper having amarkedly low oxygen content and a high degree of electrical conductivitywhile retaining suflicient ductility to facilitate subsequent workingthereof.

- It has been determined by extensive experimentation that copper havingso small an oxygen content that it will not embrittle when subjected toheat in an atmosphere of hydrogen may be obtained if a'deoxidizing agentis intimately enough mixed with tough pitch copper in a crucible coatedwith a material which will not contaminate the deoxidized copper.Experiments have also proved that copper having an oxygen content knownto be less than 005% and which -will not embrittle when heated in anatmosphere of hydrogen may be produced by intimately mixing a reagentsuch as calcium boride, aluminum boride, or silicon boride with toughpitch copper in the type of crucible described. In general, thesefeatures constitute the subject matter of the present invention.

Application med September 9, 1880. Serial l lo. 480,821.

The preferred form of the invention comprises providing a clay graphitecrucible,

lining the crucible with a material devoid of any substance which willcontaminate the copper when the molten bath thereof is poured intothecrucible, sprinkling a small amount of calcium boride over the surfaceof the crucible thus treated, pouring molten tough pitch copper into thecrucible, and adding to the stream of copper'being poured co per foilcapsules containin calcium bori e. An aluminum oxide was has beendetermined to be a very'satisfactory surfacing material for lining thecrucible, and if su-fli ciently pure will not be reduced to metallicelements which might be dissolved into the copper. In the preferred formof the invention, the steps thereof are as follows: First, meltingthe-copper in a mother furnace, oxidizing it by any of the well knownmethods to minimize the impurities in the copper, and

while in a molten state poling it thereby reducing the oxygen content tofrom approximately .03% to approximately .08% of oxygen by weight;second, covering the bath in the mother furnace with a carbonaceousmaterial such as charcoal; third, ladling the molten tough pitch copperso produced from ,the mother furnace into a heated crucible to I whicha. lining has been applied by washing or painting the interior of thecrucible with a mixture of about 20% aluminum oxide (A1 0,) in water,and upon which lining calcium boride has been sprinkled; fourth, as themolten tough pitch cop er is poured from the ladle into the crucib e,adding to the stream being-poured copper foil capsules containingcalcium boride in the ratio of approximately one gram for each pound ofmetal being treated.

This method of mixing calcium boride with molten tough pitch copperresults in an intimate mixture of the reagent with the copper. Copperproduced by the method of the present invention has an oxygen content ofless than .005% by weight. In fact, the oxygen content is so low thatwhen copper treated in this manner is heated to between 850 C. and 950C. in an atmosphere of hydrogen, no

appreciable amount of embrittling occurs.

. wherein a clay Althou h a specific embodiment of the invention as beendescribed hereinbefore, graphite crucible lined with a layer of alumlnumoxide (A1,,O.) is used and foil capsules containing calcium boride areadded to the stream of molten copper being poured into the crucible itis to be understood that a pure silica crucible might be used andcalcium boride and copper filings or dust mi ht be compressed intopellets and added to t e stream of molten copper. Numerous othersubstitutions might be made without depart-in from the scope of theinvention which is lmited only by the scope of the appended claims.

What is claimed is:

1. A method of producing copper substantially free from oxygen which comrises poling molten copper in a mother urnace to reduce the oxygencontent thereof to from approximately .03% to a proximately .08% byweight, providing a c ay graphite crucible lined with a layer ofaluminum oxide, sprinkling the lining with calcium boride, ladling themolten copper from the mother furnace and pouring it into the crucible,and

adding copper containers containing calcium boride to the stream ofmolten metal being poured into the crucible to mix intimately thecalcium boride with the molten copper.

2. A method of producing copper substantially free from oxygen whichcomprises poling molten copper in a mother furnace to reduce the oxygencontent thereof to from approximately .03% to approximately .08% byweight, providing a clay. graphite crucible lined with a layer ofaluminum oxide, sprinkling the lining with calcium boride, ladling themolten copper from the mother furnace and pouring it into the crucible,and adding copper capsules containing calcium boride in the proportionof one gram of calcium boride to one pound of metal being treated to thestream of molten metal being poured into the crucible to mix intimatelythe calcium boride with the molten copper.

In witness whereof, I hereunto subscribe my name this 29th day of AugustA. D., 1930.

JAMES W. SCOTT.

